Laminated glass



" April l1,` 1939. i w.A H. Moss i 2,153,585

LAMINATED `GLASS original Filed Marohi, 193e I WB Skil/Lav@ Patented 11,1939

`uNl'llsD s'rA'rss PATENT oFFlcE LAmNArED GLASS `William Henry Moss, London, England, assigner to Celanese Corporation of Vration of Delayvare America. a corlwriginal application March 4, 1936, Serial No.

Divided and this application February 4, 1937, Serial N0. 124,027. In Great Britain March 13, 1935 comme. (01.49.41). f l.

' This invention relates to the production. oi `compositions and articles containing new condensation products. and more'particularly to the productionofcompositions and articles contain- .ing gelatin and new condensation products of Dlyhydricfalcohols with polybasic acids. This application is a.y division of my co-pending application S. No. ,6'l,149, filed March 4, 1936.

It has' been found'that the products obtainlo able' syiebnllexising polyhydric alcohols ,with hy- `fdmxyy polycarboxylicacids or acidylated hydroxy poiycarboxylic acids, in' the presence or. absence l`."o'f aldehydes, or with vcondensation products of hydroxy polycarboxylic acids with aldehydes, and

the accompanying drawing the ligure is a crosssection of safety glass made in accordance with 30 one form of my invention.

The new condensation products may be pro- 4duced by the condensation of polyhydric alcofhols with hydroxy polycarbcxyllc acids in the presence or absence of -aldehydea or with acidylated hydroxy polycarboxylic acids. `or with condensation products of hydroxy4 polycarboxylic acids with aldehydes.' the condensation being stopped before the productbecomes water insoluble. The invention includes vcompositions of of splinterlessglass by processes involving :the

use oi the condensation products asadhesivei. I'he term polyhydric alcohol as employedin'f the present specification includes" `both alcohols and alcohols the moi'ecules'of'which con-:`

tain three or more'hydroxylgrouparSimilarly.' the term #polycarboxylic aci as employed Y 'the present tionincludes bothidicarbcllylicjaciclsI and molecules of which contain three or more carboxyl-groups.

i The condensation products may be obtained for example by th condensation of a polyhydric alcohol such for example as glycerol. glycol, di-

u ethylene glycol. ori r0i y1enc glycol, Greven matter containing gelatin andthA newcondene sation products, and also includea'theproduction' mannitol.. or 'other higher polyhydric alcohol, with a hydroxy polycarboxylic acid, or with an acidylated hydroxy polycarboxylic acid or, with a condensation product of a hydroxy polycar boxylic acid with an aldehyde such, for example, as formaldehyde. boxylic .acids are citric acid. .tartaric acid, methylene citric acidV and acetyl citric acid. Preferably the alcohol employed contains a hydroxy substituent on each of two adjacent carbon atoms. Instead of condensing -a condensation product of a hydroxy polycarboxylic acid and an aldehyde with a polyhydric alcohol, an aldehyde, e. g. formaldehyde or paraformaldehyde may be mixed-with the polyhydric alcohol and the hydroxy polycarboxyiic acid -and condensation-eifected between all three reactants. Again, a polyhydric alcohol may be condensed with an laldehyde and the condensation `product obtained reacted with the polycarboxylic acid. For instancaglycerol may be condensed with formaldehyde, yielding formal glycerol, which is reacted with citric acid according to the invention. y

Condensation of the reactants to produce the products of the present invention may be brought about by simple heating in` the absence of 'catalysts. catalysts, e. g. acid or basic catalysts may, however, be employed. The reaction is advantageously continued until a product is obtained which is soluble in water and is capable of forming lms, e. g. upon evaporation of water from a thin layer of its aqueous solution. Preferably condensation is stopped only shortly before the stage is reached when a water-insoluble product is obtained.

Of particular value are the condensation prod- Examples of suitable polycaructs obtainable by. the condensation of glycerol the' reactants being employedin each case. Thus.

for example,gequimolecular proportions of meth-- jfylciepcitrlcaela and glycerol; or of citric acid .anc glycerol,A maybeheatea-atlso" c. until a' test sample gels when. heated in a glass tube in oil Vbath,loi 10 minutes at 185 to 190 C. or slightlyv. higher temperature. The condensation of methylene citric acid and glycerol under these conditions usually takes about an hour and a quarter. v

' The condensation products of the present invention are soluble in water and are compatible with gelatin and with cellulose esters and ethers, such, for example, as cellulose acetate, cellulose formate, cellulose butyrate, cellulose nitroacetate or nitrocellulose, or ethyl cellulose, methyl cellulose, or benzyl cellulose. With cellulose ace- Atate they form clear films which are softened by waterland have adhesive properties.

Films, foils, and other compositions contain- Vits light fastness, is particularly suitable for use in ther reinforcing layer in splinterless glass. It is also well known that few Ysubstances possess the strong adhesion for glass possessed by gelatin. Unfortunately, adhesion between gelatin and cellulose acetateis poor. The condensation products of the present invention, however, may be employed to give very strong adhesion between cellulose acetate and gelatin and are therefore of especial value for the productionof' splinterless glass wherein a cellulose acetate reinforcement is secured 'to glass through a gelatin Vadhesive layer. When` used forfthis purpose' the condensation product may be incorporated in the cellulose acetate reinforcement, orl inthe gelatin, or it may form a thin layer between-the cellulose acetate and gelatin.V Y 1 The following examples illustrate the production ofthe condensation products of the present vist invention and adhesives and other products con- Example 1 20.4 parte of methylene citric-acid are heated with 6 parts of glycerol in an. open vessel at 180 C. until a-test sample gels when heated for 10 minutes at 185 to 190 C. in a glass tube in an oil bath. At this stage the product is yellow in colour and is just hard at ordinary temperatures.

' 'Ihe time taken to reach this stage is about 1 hour and minutes. Instead of using methylene citric acid and glycerol in this example, condensation may be effected between citric acid, glycerol, and paraformaldehyde. r 1

Example 2 2o parte er cime eeid and 9.2 parte of glycerol are condensed as in Example 1.

In place of glycerol, glycol or formal glycerol may be employed and in place of citric acid, methylene citric acid, acetyl citric acid or tartaric acid may be employed, the proportions being substantially equirnolecular.

. Example 3 This exampleillustrates theuse of the condensationproducts of the present invention in the manufacture of splinterless glass. l

I Two pieces of glass are each sprayed on one v surface with a solution containing 1/2 to 2.5% of gelatin in water or in a mixture of lwater and lalcohol and are then dried either in the air or at The condensaf tion product obtained is clear and colourless.

uct.

ansatius 1 or 2 is then sprayed on to the surface of the gelatin and the sheets again dried. A thin sheet of plasticised cellulose acetate is dipped into a softening solution, consisting of 90 parts of triacetin and 10 parts of alcohol or ethyl lactate and immediately after dipping placed between the coated sides of the glass sheets. l 'I'he assembly is then pressed in a steam-heated press for 10 minutes using pounds per square inch steam pressure and 50 pounds per square inch hydraulic pressure. splinterless glass the component parts of which adhere strongly to each other is obtained.

Example 4 An adhesive suitable for use with celluloseacetate foil is made up from the following:-

Parts Condensation product obtained from methylene citric acid and glycerol according to Example 1 12.4 Gelatin 0.9 Water.. 14

The condensation product and the gelatin are dissolved in separate portions of the Water and the resultant solutions mixed together, yielding a composition which is liquid at ordinary temperatures. It constitutes an excellent adhesive for cellulose-acetate foil and may be used for instance for sealing wrappings of cellulose-acetate coated with layers of gelatin 2 and 6 respectively,

and 4 is a sheet of cellulose acetate plastic bonded to each of said gelatin layers by layers 3 and 5 each comprising a water-soluble condensation product according to the invention.

Having described my invention what I desire to secure by Letters Patent is:

l. Safety glass comprising a sheet of glass coated with a layer of gelatin and a sheet of cellulose-derivative Vplastic bonded to said gelatin by means of a water-soluble condensation product of a polyhydric alcohol with a compound selected from the group consistingof citric acid, tartaric acid, methylene citric acid and acetyl citric acid.

2. Safety glass comprising a sheet of glass coated with a layer of gelatin and a sheet of cellulose-acetate plastic bonded to said gelatin by Ameans of a water-soluble methylene-citricacid/polyhydricealcohol condensation product.

3. Safety glass Vcomprising a sheet of glass coated with a layer of gelatin and a sheet of cellulose-acetateplastic bonded to said gelatin by a layer comprising a water-soluble condensation product of a polyhydric alcohol with a compound selected frorn the group consisting of citric acid, tartaric acid, methylene citric acid, and acetyl citric acid.

4. Safety glass comprising a sheet of glass coated with a layer of gelatin and a sheet of cellulose-acetate plastic bonded to said gelatin by a layer comprising a watersoluble methylenecitric-acid/polyhydric-alcohol condensation prod- HENRY MOSS. 

